B. pertussis produces various substances with striking biological activities. One of these substances is a protein that has been purified and crystallized by us and named pertussigen. It is a substance that in nanogram doses induces an increased immune response to many antigens; in particular it increases the production of IgE antibodies. It augments the intensity and duration of delayed type hypersensitivity (DTH), the induction of experimental allergic encephalomyelitis (EAE) and the production of insulin. It also induces lyphocytosis and increases the number of plasma cell precursors in the bone marrow of mice. Pertussigen has a molecular weight of around 100,000 and it is composed of 5 peptide chains. The role of the 5 peptides on the various activities of pertussigen is not well known, and this is under investigation. In addition, pertussigen is an excellent adjuvant to certain vaccines and this aspect is also under investigation in collaboration with others.